Summary Rules for Naming Alkenes

The following rules summarize the lUPAC system for naming alkenes  

Select the longest chain or largest ring that contains the largest possible number of double bonds, and name it with the -ene suffix. If there are two double bonds, the suffix is -diene-, for three, -triene-, forfour, -tetraene, and so on. 

Number the chain from the end closest to the double bonds. Number a ring so that the double bond is between carbons I and 2. Place the numbers giving the locations of the double bonds in front of the root name (old system) or in front of the suffix -ene, -diene, etc. (new system). 

Name substituent groups as in alkanes, indicating their locations by the number of the main-chain carbon to which they are attached. The ethenyl group and the propenyl group are usually called the vinyl group and the allyl group, respectively. 

For compounds that show geometric isomerism, add the appropriate prefix cis- or trans-, or E- or Z-. Cycloalkenes are assumed to be cis unless named otherwise. 

---

The Orbital Description of the Alkene Double Bond 286 7-3 Elements of Unsaturation 287 7-4 Nomenclature of Alkenes 289 7-5 Nomenclature of Cis-Trans Isomers 291 Summary Rules for Naming Alkenes 293 7-6 Commercial Importance of Alkenes 294 7-7 Stability of Alkenes 296 7-8 Physical Properties of Alkenes 302... 

---